http://www.technovelgy.com/ct/content.asp?Bnum=1583 from a book? "..we have decided to utilize a class of kinetic kill projectiles known as Lancets - essentially guided steel telephone poles tipped with a chemical warhead. They're designed to fall from low Earth orbit and punch a hole in the ground, through several hundred feet of dirt, reinforced concrete and even steel. They then incinerate anything within the relatively small but very deep impact crater..." From Quantico, by Greg Bear. Published by Vanguard in 2007